The present invention relates, in general, to the field of signal wraps for transducer fault isolation. More particularly, the present invention relates to a signal wrap for a telephone station for remote isolation and identification of malfunctions in end-user telephone equipment such as a handset microphone and handset receiver and an associated sound source and hand receiver. The term "handset receiver", as used herein, refers to the handset earpiece speaker device which receives electrical signals and provides acoustic signals in response thereto.
In fault isolation and error detection, techniques have been developed in conventional circuitry to wrap an incoming signal and return it to a return path for A-B comparison. From this information, deduction can be made about the proper operation of the involved circuit. By partitioning the circuit, more complete information can be derived. This technique can be applied to telephone circuits but it has not heretofore been applied to the transducers of the telephone itself.
A major problem in the telephone industry is that the provider of the service, in this case the telephone company, can easily determine whether their in-office equipment is working, but a greater problem is presented in determining the operating condition of equipment at the other end of the line. Expense in time, money and effort is involved in sending a repairman to determine the operating condition of a user's telephone handset, cord etc. While the telephone company has been able to send a ringing signal to test the impedence of the interconnecting line, such a wrap signal does not check the handset itself. As is obvious, it is simply not feasible to call the user and inquire as to the operating condition of his telephone, especially if it isn't working, or no one was at home.